You know what would be an interesting solution? Make it so that the 3x3 AOE that boilers have does no damage to marines, but instead immediately applies weak acid to structures in the radius. Make it use all of the boiler’s plasma if you don’t want them spamming it. Then you have a guaranteed destruction of an area of cade line, but it doesn’t happen immediately & doesn’t completely invalidate cades, just turns them into what they’re really supposed to be: a time-buyer for either counter attack or evac.